LOL thanks Gran. I got a 20L Critter Cage for $39.99 @ Petco, couldn't pass that deal up. You mentioned the UTH should take up 1/3 of the tank, no more/no less. When I put the UTH on for measurement purposes (lengthwise in the package) it takes up 1/3 of the tank, but there is a 2.5'' space behind it and in fornt of it that is not covered by the heater. When I place it the other way it takes up 1/4 of the tank. The package says its for 10-20G terrariums. What way should I place it on? I am going to adhere it to a piece of tile, so I can reuse it on another tank if need be.